Suchet stars in the Sky1 adaptation of Pratchett's novel Going Postal but admitted that he didn't know much about the author's work.
"I was never into the cult of Discworld," he told Total Sci-Fi Online. "But having seen the films [Hogfather and The Colour Of Magic] and having read the book of Going Postal, I can easily find myself picking up another Terry Pratchett.
"He's one of our most imaginative writers. One of the greatest gifts of any creative person is imagination. I've often said that the magic word which opens the imagination is 'if'... For his genre, he's the 'if' writer."
Suchet's co-star Charles Dance, who plays Lord Vetinari, added: "Terry has created an almost Dickensian world, where so many of the characters have onomatopoeic names - it was a joy to do."
Going Postal begins on May 30 at 6pm on Sky1.